The present invention relates to an apparatus for forming and conveying stacks of documents at a high speed.
Apparatus for forming and conveying stacks of documents are well known. For example, U.S. Pat. No. 4,229,134 to Reist discloses a prior apparatus for forming and conveying stacks of documents. The Reist patent discloses a vertical stacker compartment into which printed documents are dropped. Two displaceable slide plates are located at the bottom of the stacker compartment. The slide plates may be "closed" and "opened" to form and then drop a stack of printed documents through a receiver chute and onto an underlying support table. The stack is then ejected from the support table by means of an ejection element, which is guided by rollers along a horizontal path across the support table. At the end of the ejection stroke, the ejection element is retracted in the reverse direction along the support table. The ejection element is driven and retracted by means of a piston-and-cylinder unit.
In another known apparatus for forming and conveying stacks of documents, the vertical stacker compartment is defined between a pair of upright and slotted partitions. Each partition is positioned between a horizontal shaft and the stacker compartment. A single row of spaced apart fingers protrude radially from each of the shafts. The shafts are rotated in opposite directions so that the fingers protrude into the stacker compartment, so that a stack may be formed on the fingers in the stacker compartment. The shafts are then further rotated in the opposite directions so that the formed stack is dropped onto a support table beneath the stacker compartment. The cycle is repeated to produce subsequent stacks. During cycling of the shafts, the fingers pass through the slots in the partitions that define the stacker compartment. The formed stacks are ejected from the support table by an ejection element that is driven across the support table and then retracted by means of a piston-and-cylinder unit.
The operating speed of prior apparatus for forming and conveying stacks of documents is limited. For example, the back and forth movement of ejection elements limits the speed at which stacks of documents may be ejected.
It is accordingly an object of the present invention to provide an apparatus for forming and conveying stacks of documents that is capable of operating at speeds significantly higher than existing machines, while maintaining a high degree of reliability and properly delivering stacks of documents. It is also an object of the present invention to provide an apparatus for forming and conveying stacks that requires less maintenance than existing machines, and that is powered by electricity rather than requiring a pneumatic supply system.